U.S. patent number 5,790,105 [Application Number 08/838,786] was granted by the patent office on 1998-08-04 for pressure sensitive resistor tablet coordinate input device.
This patent grant is currently assigned to SMK Corporation. Invention is credited to Osamu Yoshikawa.
United States Patent |
5,790,105 |
Yoshikawa |
August 4, 1998 |
Pressure sensitive resistor tablet coordinate input device
Abstract
A pressure sensitive resistance tablet coordinate input device
is provided which enables the cursor to be moved to a desired
position on a PC display by pressing a tablet sheet (6) with a
stylus, permits the stylus press-shift operation at the center of
the tablet sheet (6) and maintains the continuity of control of the
cursor movement even if the pressure to the tablet is once removed.
The device is selectively switchable between an absolute value
output data in which pressed-position data (x.sub.n,y.sub.n) is
used as cursor control data (X.sub.n,Y.sub.n) or a relative value
output mode in which relative position data is calculated by
comparing pieces of pressed-position data before and after the
stylus press-shift operation on the tablet sheet (6). The relative
position data thus calculated is used as the cursor control data
(X.sub.n,Y.sub.n). Since either one of the two modes of operation
can be selected in accordance with the contact resistance value
r.sub.P at the position of the tablet being pressed, it is possible
to control the cursor movement corresponding to the operation, only
by changing the method for pressing the tablet sheet (6).
Inventors: |
Yoshikawa; Osamu (Tokyo,
JP) |
Assignee: |
SMK Corporation (Tokyo,
JP)
|
Family
ID: |
14636946 |
Appl.
No.: |
08/838,786 |
Filed: |
April 10, 1997 |
Foreign Application Priority Data
|
|
|
|
|
Apr 12, 1996 [JP] |
|
|
8-114408 |
|
Current U.S.
Class: |
345/173;
178/18.05; 178/19.04; 345/156; 345/157; 345/174; 345/179 |
Current CPC
Class: |
G06F
3/045 (20130101); G06F 3/03547 (20130101) |
Current International
Class: |
G06F
3/033 (20060101); G09G 005/00 () |
Field of
Search: |
;345/179,174,173,156,157
;178/18,19 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hofsass; Jeffery
Assistant Examiner: Mannava; Ashok
Attorney, Agent or Firm: Armstrong, Westerman Hattori,
McLeland & Naughton
Claims
What is claimed is:
1. A pressure sensitive resistor tablet coordinate input device
which comprises:
a tablet sheet (6);
stylus pressure detecting means (16) for detecting an application
of stylus pressure to said tablet sheet (6);
position detecting means (18) for generating pressed-position data
(x.sub.n,y.sub.n) indicating a position on said tablet sheet (6)
where a stylus is being pressed;
storage means (19) for storing said pressed-position data
(x.sub.n,y.sub.n) at least until a next pressed-position data is
generated;
output data generating means (21) for generating, from said
pressed-position data (x.sub.n,y.sub.n), absolute output data
(X.sub.n,Y.sub.n) for controlling a cursor movement on a display
(5) of a personal computer (1); and
data output means (24) for outputting said absolute output data
(X.sub.n,Y.sub.n) to said personal computer (1) and which controls
said cursor movement on said display in response to an operation of
pressing said tablet sheet (6);
wherein said output data generating means (21) can selectively be
put in any one of an absolute value output mode, in which said
output data generating means uses said pressed-position data
(x.sub.n,y.sub.n) as said absolute output data (X.sub.n,Y.sub.n),
and an relative value output mode, in which said output data
generating means uses said absolute output data (X.sub.n,Y.sub.n)
obtained by adding immediately preceding absolute output data
(X.sub.n-1,Y.sub.n-1) with relative position data (x.sub.n
--x.sub.n-1,y.sub.n --y.sub.n-1) indicative of a relative shift
amount of a stylus on said tablet sheet (6) before and after a
current stylus press-shift operation is completed is completed;
and
wherein said output data generating means (21) generates said
absolute output data in either one of said absolute value output
modes and said relative value output mode selected in accordance
with a contact resistance value r.sub.P at said position on said
tablet sheet where said stylus is being pressed.
2. A pressure sensitive resistor tablet coordinate input device
which comprises:
a tablet sheet (6);
stylus pressure detecting means for detecting an application of
stylus pressure to a tablet sheet (6);
position detecting means for generating pressed-position data
(x.sub.n,y.sub.n) indicating the position on said tablet sheet (6)
where said stylus is being pressed;
storage means (19) for storing said pressed-position data
(x.sub.n,y.sub.n) at least until a next pressed-position data is
generated;
output data generating means (39) for computing relative position
data (x.sub.n --x.sub.n-1,y.sub.n --y.sub.n-1) by comparing pieces
of pressed-position data before and after a current stylus
press-shift operation on said tablet sheet (6) and for generating,
from said relative position data (x.sub.n --x.sub.n-1,y.sub.n
--y.sub.n-1), relative output data (X'.sub.n,Y'.sub.n) for
controlling a cursor movement; and
data output means (24) for outputting said relative output data
(X'.sub.n,Y'.sub.n) to a personal computer and which controls said
cursor movement on a display of said personal computer in response
to an operation of pressing said tablet sheet (6);
wherein when said stylus pressure applied to said tablet sheet (6)
is detected again after said stylus pressure was once removed, said
output data generating means (39) can selectively be put in any one
of an absolute value output mode, in which said output data
generating means computes said relative position data (x.sub.n
--x.sub.n-1,y.sub.n --y.sub.n-1) by comparing pressed-position data
(x.sub.n-1,y.sub.n-1) at a position where said stylus pressure to
said tablet sheet was removed and pressed-position data
(x.sub.n,y.sub.n) at a position where said stylus pressure to said
tablet sheet was detected again and generates said relative output
data (X'.sub.n,Y'.sub.n) from said computed relative position data
(x.sub.n --x.sub.n-1,y.sub.n --y.sub.n-1), and a relative value
output mode, in which said output data generating means nullifies
said pressed-position data (x.sub.n-1,y.sub.n-1) at said position
where said stylus pressure was removed from said tablet sheet and
does not generate said relative output data (X'.sub.n,Y'.sub.n);
and
wherein said output data generating means (39) generates said
relative output data in either one of said absolute value output
modes and said relative value output mode selected in accordance
with a contact resistance value r.sub.P at said position on said
tablet sheet where said stylus is being pressed.
3. The pressure sensitive resistance tablet coordinate input device
of claims any one of 1 and 2, of said output data generating means
(21), (39) is chosen by discriminating between a contact resistance
value r.sub.1P by pressing said tablet sheet with said stylus and a
contact resistance value r.sub.2P by pressing with a finger.
4. The pressure sensitive resistance tablet coordinate input device
of any one of claims 1 and 2, wherein any one of said absolute
value output mode and said relative value output mode of said
output data generating means (21), (39) is chosen through
utilization of a difference between contact resistance values
r.sub.P by pressing said tablet sheet with a first kind of said
stylus and a second kind of said stylus, each having tablet contact
portions of different curvatures.
5. The pressure sensitive resistance tablet coordinate input device
of any one of claims 1 and 2, wherein any one of said absolute
value output mode and said relative value output mode of said
output data generating means (21), (39) is chosen according to said
contact resistance value r.sub.P at a position on said tablet sheet
(6) where pressure thereto is detected.
6. The pressure sensitive resistance tablet coordinate input device
of claim 3, wherein any one of said absolute value output mode and
said relative value output mode of said output data generating
means (21), (39) is chosen according to said contact resistance
value r.sub.P at a position on said tablet sheet (6) where pressure
thereto is detected.
7. The pressure sensitive resistance tablet coordinate input device
of claim 4, wherein any one of said absolute value output mode and
said relative value output mode of said output data generating
means (21), (39) is chosen according to said contact resistance
value r.sub.P at a position on said tablet sheet (6) where pressure
thereto is detected.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pressure sensitive resistor
tablet coordinate input device which controls the movement of a
cursor on the display screen of a personal computer in accordance
with the position on a tablet sheet where the pressure sensitive
resistor tablet coordinate input device is being pressed.
2. Description of the Prior Art
With recent developments in GUI (Graphical User Interface)
environments, a mouse has come into wide use as a coordinate input
device for personal computers (hereinafter referred to simply as
PCs).
That is, the mouse is dragged on an operation pad and relative
output data (X'.sub.n,Y'.sub.n) is generated from relative position
data (x.sub.n --x.sub.n-1,y.sub.n --y.sub.n-1) representing the
distance dragged and is fed to a PC. A device driver of the PC adds
the relative output data (X'.sub.n,Y'.sub.n) input thereto via an
input/output or I/O port from the mouse to cursor control data
(CX.sub.n-1,CY.sub.n-1) having represented so far the absolute
position of the cursor on the PC screen to generate new cursor
control data (CX.sub.n,CY.sub.n), and controlling the cursor to
move to the position on the PC screen indicated by the new cursor
control data (CX.sub.n,CY.sub.n). A user moves the cursor to the
icon on the screen while at the same time manipulating a mouse
switch to input into the PC an instruction specified by the
icon.
Since the mouse needs to be dragged on the operation pad as
mentioned above, portable PCs of the type which have no mouse
manipulating space, usually employ, as a substitute for the mouse,
such a low-profile pressure sensitive resistor tablet coordinate
input device 107 as shown in FIG. 8 which has a tablet sheet 6 as
an input surface.
The pressure sensitive resistor tablet coordinate input device 107
detects the position of pressure applied to the tablet sheet 6 in
the same way as position detecting facilities used in a known
resistance contact type tablet or similar. When moving a finger or
stylus on the tablet sheet while pressing the finger or stylus,
tablet-pressed-position data (x.sub.n,y.sub.n), indicating the
position of the pressure applied to the tablet sheet 6, is detected
upon each detection of the tablet-pressed position. The pressure
sensitive resistor tablet coordinate input device 107 provides the
tablet-pressed-position data (x.sub.n,x.sub.y) as absolute output
data (X.sub.n,Y.sub.n) to a PC 1. As referred to above, a device
driver 3 of the PC 1 uses the absolute output data
(X.sub.n,Y.sub.n) input thereto via an I/O port 4 as the cursor
control data (CX.sub.n,CY.sub.n) indicating the absolute position
of the cursor on a display 5, and controlling the cursor to move to
the position on the display 5 expressed by the cursor control data
(CX.sub.n,CY.sub.n) as is the case with the mouse 2.
Thus, by shifting the position of the pressure applied to the
tablet sheet 6, the cursor movement can be controlled in the same
manner as in the case of using the mouse.
As referred to above, the conventional mouse requires space for
manipulation thereof. Further, the relative output data
(X'.sub.n,Y'.sub.n) representing the distance over which the mouse
is being dragged is fed to the PC, so that when the position (O) of
the cursor and the position (A) of the icon are spaced apart from
each other on the display 5 of the PC 1 as depicted in FIG. 7, the
relative position data (x.sub.n --x.sub.n-1,y.sub.n --y.sub.n-1)
must be provided again and again to move the cursor to the position
(A) of the icon. Hence, the mouse 2 needs to be dragged by a
distance corresponding to that from the position (O) to (A).
Moreover, since the relative output data (X'.sub.n,Y'.sub.n) is
always provided during the dragging of the mouse 2, the cursor
movement leaves a continuous or uninterrupted locus. This is not
suitable for a character input in character recognition, for
instance. That is, as shown in FIG. 7, in the case of drawing a
Japanese character "" on the display 5, it is necessary that the
locus of the cursor moved to a position A, needs to start again at
a position B. Should the mouse 2 be moved in position from A' to B'
on the operation pad, the locus of the cursor movement is also
drawn between the positions A and B on the display screen 5 as
shown and is indistinguishable from the locus between the positions
O and A. For this reason, the locus of the cursor movement between
the points A and B must be cancelled. This requires another switch
input to discriminate the manipulation for the unnecessary cursor
movement from the normal manipulation.
In the conventional pressure sensitive resistor tablet coordinate
input device 107, the tablet-pressed position (x.sub.n,y.sub.n) is
used as the absolute position to create the cursor control data
(X.sub.n,Y.sub.n). Hence, as shown in FIG. 8, when pressing the
tablet sheet 6 at the position (C') corresponding to the icon on
the display screen 5, the cursor will immediately move to the
position (C) corresponding to the tablet-pressed position; thus,
the cursor can be controlled to move to a desired position by
outputting the tablet-pressed-position data (x.sub.n,y.sub.n) only
once. Also in the above-mentioned character input, it is possible
to form spaced-apart loci of cursor movements by stopping the
pressing of the tablet sheet 6 at one position and then resuming it
at a different position.
Yet the conventional pressure sensitive resistor tablet coordinate
input device 107 has the following disadvantages. First, the tablet
sheet 6 always needs to be pressed at the position corresponding to
that of the cursor on the display, so that in the case of moving
the cursor from a position (C) to (D), for instance, on the display
as shown in FIG. 8, it is necessary to move, for example, a stylus
from a position (C') to (D') in a narrow area at the upper right
corner of the tablet sheet 6 while pressing the stylus thereto.
Combined with the narrow operation area of the tablet sheet 6, it
is cumbersome to press the tablet sheet 6.
Second, in the case of inputting, for example, a pattern by loci of
cursor movements, it is hard to resume pressing the tablet sheet 6
at the position where the previous pressing was discontinued.
Accordingly, in the case of drawing a graphic form or similar by
loci of cursor movements, there is a strong possibility that the
operation cannot be performed continuously and must be started over
again.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a
pressure sensitive resistor tablet coordinate input device which
permits cursor movement to a desired position on the display by one
press on the tablet sheet, enables the stylus press-shift operation
on the tablet sheet to be done at the center thereof and retains
the continuity of the cursor movement control even if the pressing
of the tablet sheet is temporarily stopped.
According to a first aspect of the present invention, there is
provided a pressure sensitive resistor tablet coordinate input
device which includes: a tablet sheet; stylus pressure detecting
facilities for detecting the application of stylus pressure to the
tablet sheet; position detecting facilities for generating
pressed-position data (x.sub.n,y.sub.n) indicating the position on
the tablet sheet where it is being pressed; storage facilities for
storing the pressed-position data (x.sub.n,y.sub.n) at least until
the next tablet-pressed-position data is generated; output data
generating facilities for generating, from the pressed-position
data (x.sub.n,y.sub.n), absolute output data (X.sub.n,Y.sub.n) for
controlling the cursor movement; and data output facilities for
outputting the absolute output data (X.sub.n,Y.sub.n) to a personal
computer. The coordinate input device controls the cursor movement
on the PC display in response to the tablet sheet pressing
operation.
The output data generating facilities can selectively be put in: an
absolute value output mode in which to use the
tablet-pressed-position data (x.sub.n,y.sub.n) as the absolute
output data (X.sub.n,Y.sub.n); and an relative value output mode in
which to use the absolute output data (X.sub.n,Y.sub.n) obtained by
adding immediately preceding absolute output data
(X.sub.n-1,Y.sub.n-1) with relative position data (x.sub.n
--x.sub.n-1,y.sub.n --y.sub.n-1) indicative of the relative stylus
shift amount on the tablet sheet before and after the current
press-shift operation. In either one of the two output modes
selected in accordance with the contact resistance value r.sub.P at
the position on the tablet sheet where it is being pressed, the
output data generating facilities generates the absolute output
data.
When the absolute output mode is selected according to the contact
resistance value r.sub.P at the position on the tablet sheet where
it is being pressed, the absolute output data generated using the
pressed-position data intact is fed to the personal computer. When
the contact resistance value r.sub.P differs from that selecting
the absolute value output mode and the relative value output mode
is selected, the absolute output data, composed of the immediately
preceding absolute output data and the relative position data
representing the relative stylus shift amount on the tablet sheet
before and after the current press-shift operation, is fed to the
personal computer.
Hence, the absolute output data in the absolute value output mode
and the absolute output data in the relative value output mode can
freely be provided, by changing the contact resistance value
r.sub.P, to the personal computer which moves the cursor by the
input thereto of the absolute output data. In the absolute value
output mode, the cursor can be moved to a desired position on the
display by one operation, besides loci of the cursor movements can
be formed at spaced-apart positions. In the relative value output
mode, the stylus press-shift operation can be performed at an
arbitrary position on the tablet sheet and the amount of distance
moved on the tablet sheet without pressing it is not included in
the relative position data, so that even if the pressure applied to
the tablet sheet is removed during the press-shift operation,
continuity will not be destroyed.
According to a second aspect of the present invention, there is
provided a pressure sensitive resistor tablet coordinate input
device which includes: a tablet sheet; stylus pressure detecting
facilities for detecting the application of pressure to the tablet
sheet; position detecting facilities for generating
pressed-position data (x.sub.n,y.sub.n) indicating the position on
the tablet sheet where the stylus pressure applied thereto; storage
facilities for storing the tablet-pressed-position data
(x.sub.n,y.sub.n) at least until the next pressed-position data is
generated; output data generating facilities for computing relative
position data (x.sub.n --x.sub.n-1,y.sub.n --y.sub.n-1) by
comparing pieces of pressed-position data before and after the
current one and for generating, from the relative position data
(x.sub.n --x.sub.n-1,y.sub.n --y.sub.n-1), relative output data
(X'.sub.n,Y'.sub.n) for controlling the cursor movement; and data
output facilities for outputting the relative output data
(X'.sub.n,Y'.sub.n) to a personal computer. The coordinate input
device controls the cursor movement on the PC display in response
to the tablet sheet pressing operation.
When the pressure applied to the tablet sheet is detected again
after the pressure was once removed, the output data generating
facilities can selectively put in: an absolute value output mode in
which it computes the relative position data (x.sub.n
--x.sub.n-1,y.sub.n --y.sub.n-1) by comparing the data
(x.sub.n-1,y.sub.n-1) on the position where the pressure to the
tablet sheet was removed and the data (x.sub.n,y.sub.n) on the
position where the pressure to the tablet sheet was detected again
and generates the relative output data (X'.sub.n,Y'.sub.n) from the
thus computed relative position data (x.sub.n --x.sub.n-1,y.sub.n
--y.sub.n-1); and a relative value output mode in which it
nullifies the data (x.sub.n-1,y.sub.n-1) on the position of the
tablet sheet where the pressure was removed therefrom and does not
generate the relative output data (X'.sub.n,Y'.sub.n). In either
one of the two output modes selected in accordance with the contact
resistance value r.sub.P at the tablet-pressed position, the output
data generating facilities generates the relative output data.
When the absolute value output mode is selected according to the
contact resistance value r.sub.P at the pressed position, relative
output data is generated from the relative position data which
represents the relative stylus shift amount from the position on
the tablet sheet where the pressure was removed therefrom to the
position on the tablet sheet where it was pressed again, and such
relative output data is fed to the personal computer. When the
contact resistance value r.sub.P is a value different from the
value accorded by the selection of the absolute value output mode,
the relative value output mode is selected and no relative output
data is created upon detection of the application of the pressure
to the tablet sheet.
Hence, the absolute output data in the absolute value output mode
and the absolute output data in the relative value output mode can
freely be fed, by changing the contact resistance value r.sub.P, to
the personal computer which moves the cursor by the input thereto
of the absolute output data. In the absolute value output mode, the
relative output data is provided which is based on the relative
stylus shift amount on the tablet sheet after the removal therefrom
of the stylus pressure, so that the cursor can be moved to a
desired position on the display by one operation. Besides, loci of
the cursor movements can be formed at spaced-apart positions by
making provision to generate the loci only while detecting the
application of the stylus pressure to the tablet sheet. In the
relative value output mode, when the application of the pressure to
the tablet sheet is detected, no relative output data is generated.
Hence, even if the pressure applied to the tablet sheet is
temporarily removed during the press-shift operation, the cursor
movement can be controlled continuously.
According to a third aspect of the present invention, the mode of
operation for the output data generating facilities is chosen by
discriminating between a contact resistance value r.sub.1P by
pressing the tablet sheet with a stylus and a contact resistance
value r.sub.2P by pressing with a finger.
The pressed area of the tablet sheet differs when pressed with a
stylus and with a finger. When the tablet sheet is pressed with the
same pressure, the contact resistance r.sub.P at the pressed
position differs with the finger and the stylus. Thus, either one
of the absolute output mode and the relative output mode can be
chosen by pressing the tablet sheet with the stylus or finger.
According to a fourth aspect of the present invention, the mode of
operation for the output data generating facilities is chosen
through utilization of a difference between contact resistance
values r.sub.P by pressing the tablet sheet with two kinds of
styluses having tablet contact portions of different
curvatures.
The pressed area of the tablet sheet differs with curvatures of
tablet contact portions of styluses. When the tablet sheet is
pressed by styluses with the same pressure, the contact resistance
r.sub.P at the pressed position differs. Hence, the absolute and
the relative output mode can selectively be used by changing the
two kinds of styluses.
According to a fifth aspect of the present invention, the mode of
operation for the output data generating facilities is chosen
according to the contact resistance value r.sub.P at the
tablet-pressed position when the application of the pressure to the
tablet sheet is detected.
In the case where the output data generating facilities is in the
absolute value output mode when the tablet sheet is being pressed,
the cursor moves from the position where the pressure was removed
to the position corresponding to that where the tablet sheet was
pressed again, whereas in the relative value output mode, the
cursor will not move when the tablet sheet is pressed. Accordingly,
by pressing the tablet sheet again after once stopping, it is
possible to select the mode, according to the contact resistance
value r.sub.P at the tablet-pressed position, to move the cursor to
the position corresponding to the pressed-position or keep on
cursor movement control despite temporary discontinuation of
pressing the tablet sheet.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a touch pad 7 which is the pressure
sensitive resistor tablet coordinate input unit according to an
embodiment of the present invention;
FIG. 2 is a circuit diagram of the touch pad 7 shown in FIG. 1;
FIG. 3 is an equivalent circuit of the touch pad 7;
FIG. 4 is a block diagram illustrating the configuration of the
touch pad 7;
FIG. 5 is an explanatory diagram showing the relationship between
the operation of the touch pad 7 and the cursor movement on a
display 5;
FIG. 6 is a block diagram of a touch pad 30 according to another
embodiment of the present invention;
FIG. 7 is an explanatory diagram showing the relationship between
the operation of a conventional mouse 2 and the cursor movement on
the display 5; and
FIG. 8 is an explanatory diagram showing the relationship between
the operation of a conventional touch pad 7 and the cursor movement
on the display 5.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to the accompanying drawings, an embodiment of the
present invention will hereinafter be described, in which the parts
corresponding to those in the prior art example are identified by
the same reference numerals.
FIG. 1 illustrates in perspective, a touch pad 7 which is a
pressure sensitive resistor tablet coordinate input device
according to an embodiment of the present invention. The touch pad
7 has a flat input surface formed by a tablet sheet 6. As shown,
there are provided in the forward portion of the touch pad 7, a
pair of left and right push-button switches 8 and 9 corresponding
to switches of the conventional mouse. Mounted on the touch pad 7
in a backward portion thereof, are two light emitting elements 11
and 12 for displaying the mode of the touch pad 7.
The touch pad 7 is connected to a PC 1 via a cable 13 connected to
the back of the PC 1. The touch pad 7 outputs absolute output data
(X.sub.n,Y.sub.n) to a device driver 3 via an I/O port 4 of the PC
1.
FIG. 2 illustrates the circuit configuration of the touch pad 7, in
which a microcomputer 10 has an AD converter 14 built-in. The AD
converter 14 has three input terminals AD1, AD2 and AD3 and adapted
to be capable of detecting potential at the respective input
terminals at the same time.
The microcomputer 10 has five input/output terminals RCHK,
IX.sup.+, OX.sup.-, IY.sup.+ and OY.sup.-, to which electronic
switches 33 to 37 are connected for switching the connections of
these terminals to internal circuits. The electronic switches 33 to
37 individually operate under the control of a switch control
circuit 15 of the microcomputer 10 to switch between the
above-mentioned terminals and the internal circuits of the
microcomputer 10 as described later on.
The tablet sheet 6 is composed of a pair of opposed X- and
Y-coordinate resistance sheets 60 and 61 coated uniformly all over
the inner surfaces thereof with resistance layers and slightly
spaced apart by dot-like insulating spacers (not shown) printed on
opposed outer surfaces thereof.
As shown, the X-coordinate resistance sheet 60 has X-side positive
and negative electrodes 60a and 60b formed thereon along opposite
marginal edges in the X-direction. The positive electrode 60a is
connected to the terminal IX.sup.+ of the microcomputer 10 and the
terminal RCHK via a variable resistor R.sub.C that serves as a
reference resistor. The negative electrode 60b is connected to the
terminal OX.sup.- of the microcomputer 10. The resistance value
r.sub.C of the reference resistor R.sub.C is a predetermined value
so adjusted as to allow ease in computing the contact resistance
value r.sub.P of the tablet sheet 6 as described later on.
Similarly, the Y-coordinate resistance sheets 61 has Y-side
positive and negative electrodes 61a and 61b formed thereon along
opposite marginal edges in the Y-direction. The positive electrode
61a is connected to the terminal IY.sup.+ of the microcomputer 10
and the negative electrode 61b the terminal OY.sup.- of the
microcomputer 10.
FIG. 4 illustrates in block form the configuration of the touch pad
7. Connected to the tablet sheet 6, composed of the X- and
Y-coordinate resistance sheets 60 and 61, are a stylus pressure
detecting circuit 16, a mode discriminating circuit 31, and a
pressed-position detecting circuit 17, which monitor the pressed
state of the tablet sheet 6 when the touch pad 7 is in a stylus
pressure detection mode, in a contact resistance detection mode,
and in X- and Y-coordinate detection modes, respectively.
Referring now to FIG. 2, the operations of these circuits will be
described.
The stylus pressure detecting circuit 16 monitors, for example, the
potential of the X-coordinate resistance sheet 61 of the tablet
sheet 6 and detects the application of stylus pressure and its
removal from potential variations which are caused when the
X-coordinate resistance sheet 61 comes into and goes out of contact
with the Y-coordinate resistance sheet 61. In the stylus pressure
detection mode, the terminal RCHK.sup.+ in FIG. 2 is connected via
the switch 33 to the power supply V.sub.CC to apply therefrom a
reference detecting voltage V.sub.CC to the X-coordinate resistance
sheet 60 via a reference resistor R.sub.C, while at the same time
the terminal IX.sup.+ is connected to the input terminal AD1 of the
AD converter 14 so as to detect the potential of the X-coordinate
resistance sheet 60. Further, the input/output terminal OY.sup.- is
connected via the switch 37 to a grounding terminal to keep the
Y-coordinate resistance sheet 61 at the ground level.
While no pressure is being applied to the tablet sheet 6, no
current flows across the resistance sheets 60 and 61, so that no
voltage drop occurs across the reference resistor R.sub.C, holding
the terminal IX.sup.+ at the potential of the power supply
V.sub.CC.
When the tablet sheet 6 is pressed in this state, a current flows
from the X-coordinate resistance sheet 60 to the Y-coordinate
resistance sheet 61 and the potential at the terminal IX+ drops
accordingly. By comparing this potential with a stylus pressure
detecting threshold value V.sub.T, it is detected whether the
tablet sheet 6 is being pressed or not.
Upon detection of the pressing of the tablet sheet 6 in the stylus
pressure detection mode, the touch pad 7 enters the contact
resistance detection mode and detects the contact resistance
r.sub.P at the tablet-pressed position P. The mode discriminating
circuit 31 selects the mode of operation of output data generating
facilities 21 on the basis of the contact resistance value r.sub.P
at the tablet-pressed position P.
In the contact resistance detection mode, the electronic switches
33 to 37 are operated under the control of the switch control
circuit 15 to connect respective input/output terminals of the
microcomputer 10 to internal circuits. That is, the terminal
RCHK.sup.+ is connected via the switch 33 to the power supply
V.sub.CC to apply therefrom the reference detecting voltage
V.sub.CC to the positive electrode 60a of the X-coordinate
resistance sheet 60 via the variable resistor R.sub.C. The
input/output terminals IX.sup.+, OX.sup.- and IY.sup.+ are
connected to the input terminals AD1, AD2 and AD3 of the AD
converter 14 via the switches 34, 35 and 36, respectively, to
detect potentials at the positive and negative electrodes 60a and
60b of the X-coordinate resistance sheet 60 and the positive
electrode of the Y-coordinate resistance sheet 61. The remaining
input/output terminal OY.sup.- is connected via the electronic
switch 37 to the grounding terminal to keep the negative electrode
61b of the Y-coordinate resistance sheet 61 at the ground
level.
FIG. 3 is an equivalent circuit diagram of the touch pad 7 in the
contact resistance detection mode. As shown, when the X-coordinate
resistance sheet 60 is pressed, a current (it) flows therefrom via
a contact resistance to the Y-coordinate resistance sheet 61 at the
position P where the resistance sheet 60 is being pressed. At this
time, the AD converter 14 is connected to each of the input/output
terminals IX.sup.+, OX.sup.- and IY.sup.+ and, if minute currents
toward them are neglected, the current (it) equally flows through
the variable resistor R.sub.C and the contact resistance
r.sub.P.
Letting potential differences across the two resistors be
represented by first and second potential differences V.sub.A and
V.sub.B, respectively, and the resistance value of the variable
resistor R.sub.C as a reference resistor by r.sub.C, the contact
resistance r.sub.P can be detected by r.sub.P =r.sub.C *V.sub.B
/V.sub.A based on the relationship V.sub.A /r.sub.C =V.sub.B
/r.sub.P.
As is evident from FIG. 3, the first potential difference V.sub.A
and the second potential difference V.sub.B can be calculated from
the predetermined reference detecting voltage V.sub.CC and a
potential V.sub.1 at the input terminal AD1 of the AD converter 14
and from potentials V.sub.2 and V.sub.3 at the input terminals AD1
and AD2 of the AD converter 14, so that the contact resistance
value r.sub.P can be computed by r.sub.P =r.sub.C *V.sub.B /V.sub.A
in the mode selector circuit.
The computation of the contact resistance value r.sub.P is free
from the current that flows in this mode. That is, even if the
current (it) flowing across the resistance sheets 60 and 61 varies
with a change in the position of contact (x.sub.P,y.sub.P) between
them, the contact resistance r.sub.P can be detected independently
of the current, and the contact resistance r.sub.P can be detected
as a parameter completely independent of the X- and Y-coordinates
(x.sub.P) and (y.sub.P) of the contact position P. Accordingly, as
long as the tablet sheet 6 is pressed under the same conditions,
the resistance value r.sub.P will remain unchanged regardless of
the tablet-pressed position. Conversely, by changing the contact
resistance value r.sub.P by changing the conditions for pressing
the tablet sheet, the mode of operation of the output data
generating facilities 21 can be selected. In this embodiment, the
boundary value between the contact resistance value r.sub.1P by
pressing with the stylus and the contact resistance value r.sub.2P
by pressing with a finger is set at r.sub.TP. When the contact
resistance value r.sub.P is larger than the boundary value
r.sub.TP, the mode decision circuit 31 construes it as the contact
resistance value r.sub.2P by pressing with the finger and supplies
a central control circuit 38 with a mode decision signal indicating
the relative value output mode. When the contact resistance value
r.sub.P is smaller that the boundary value r.sub.TP, the mode
decision circuit 31 construes it as the contact resistance value
r.sub.1P by pressing with the stylus and supplies the central
control circuit 38 with a mode decision signal indicating the
absolute value output mode.
When the application of the stylus pressure is detected and the
mode decision signal is output, the touch pad 7 goes into the X-
and Y-coordinate detection modes and detects the tablet-pressed
position in the pressed-position detecting circuit 17. The
detection of the X- and Y-coordinates of the tablet-pressed
position P is carried out by forming a potential gradient in the X-
and Y-coordinate resistance sheets 60 and 61 alternately with each
other.
In the X-coordinate detection mode, the input terminal IX.sup.+ is
connected via the electronic switch 34 to the power supply V.sub.CC
to feed therefrom the reference detecting voltage V.sub.CC to the
positive electrode 60a of the X-coordinate resistance sheet 60
through the terminal IX.sup.+, while at the same time the
input/output terminal OX.sup.- is grounded via the electronic
switch 35 to ground the negative electrode 60b of the X-coordinate
resistance sheet 60, forming therein a uniform potential
gradient.
On the other hand, the input/output terminal OY.sup.- connected to
the Y-side negative electrode 61b is disconnected therefrom by the
electronic switch 37 to prevent a current flow to the Y-coordinate
resistance sheet 61 from its position of contact with the
X-coordinate resistance sheet 60, while at the same time the
input/output terminal IY.sup.+ is connected via the electronic
switch 36 to the input terminal AD3 of the AD converter 14, thereby
detecting the potential at the pressed position P via the positive
electrode 61a of the Y-coordinate resistance sheet 61.
Since the uniform potential gradient is generated in the
X-coordinate resistance sheet 60, the potential V.sub.xP detected
at the input terminal AD3 of the AD converter 14 can be used to
compute and detect the X-coordinate (x.sub.P) of the contact
position P by the pressed-position detecting circuit 17.
After the detection of the X-coordinate, the touch pad 7 is
similarly put in the Y-coordinate detection mode to detect the
Y-coordinate. That is, the electronic switches 36 and 37 are
operated to feed the reference detecting voltage V.sub.CC to the
positive electrode 61a of the Y-coordinate resistance sheet 61 and
ground the negative electrode 61b, generating a uniform potential
gradient in the Y-coordinate resistance sheet 61. Further, the
electronic switch 34 connected to the negative electrode 60b of the
X-coordinate resistance sheet 60 is turned off to prevent a current
flow thereto from its position P of contact with the Y-coordinate
resistance sheet 61 and the input/output terminal IX.sup.+
connected to the X-side positive electrode 60a is connected via the
electronic switch 35 to the input terminal AD1 of the AD converter
14 to detect the potential at the contact position P from the
X-side positive electrode 60a.
As is the case with the detection of the X-coordinate, the
Y-coordinate (y.sub.P) of the contact position P is detected by the
pressed-position detecting circuit 17 by computation from the
potential V.sub.yP detected at the input terminal AD1 of the AD
converter 14.
Thereafter, the touch pad 7 is returned to the stylus pressure
detection mode and unless it is decided that the stylus is no
longer pressed to the tablet sheet 6, the touch pad 7 repeatedly
operates in the contact resistance detection mode and the X- and
Y-coordinate detection modes, deciding the mode of operation of the
output data generating facilities 21 and detecting the X- and
Y-coordinates (x.sub.P) and (y.sub.P) of the contact position
P.
As depicted in FIG. 4, the pressed-position detecting circuit 17
outputs the thus periodically detected pressed-position data
(x.sub.n,y.sub.n) to a pressed-position data correcting and
generating circuit 18. The pressed-position data correcting and
generating circuit 18 is connected to the stylus pressure detecting
circuit 16, the pressed-position detecting circuit 17 and the
central control circuit 38. After the detection of the application
of the stylus pressure to the tablet sheet 6 by the stylus pressure
detecting circuit 16, the circuit 18 correlates a plurality of
pieces of pressed-position data (x,y) input thereinto from the
pressed-position detecting circuit 17 and cancels abnormal pieces
of pressed-position data (x,y), generating pressed-position data
(x.sub.n,y.sub.n).
The output of the pressed-position data correcting and generating
circuit 18 is connected to the pressed-position data storage
circuit 19. Upon each generation of absolute output data
(X.sub.n,Y.sub.n) by the absolute output data generating circuit 21
described later, the storage circuit 19 stores the pressed-position
data (x.sub.n,y.sub.n) provided from the pressed-position data
correcting and generating circuit 18 at that time.
A relative position data calculating circuit 20 is one that, upon
each direct input thereinto of the pressed-position data
(X.sub.n,y.sub.n) from the pressed-position data correcting and
generating circuit 18, calls up from the pressed-position data
storage circuit 19 the pressed-position data (x.sub.n-1,y.sub.n-1)
stored previously when the absolute output data
(X.sub.n-1,Y.sub.n-1) was generated and uses the difference between
the two pieces of data to calculate relative position data
k(x.sub.n --x.sub.n-1,y.sub.n --y.sub.n-1). Upon each input of new
pressed-position data (x.sub.n,y.sub.n) from the pressed-position
data correcting and generating circuit 18 into the relative
position data calculating circuit 20, the relative position data
k(x.sub.n --x.sub.n-1,y.sub.n --y.sub.n-1) is calculated and fed to
the absolute output data generating circuit 21.
The left and right push-button switches 8 and 9 mounted on the
touch pad 7 are each connected to a switch depression detecting
circuit 22 to detect the depression of the switch. The switch
depression detecting circuit 22 is connected to the central control
circuit 38 and the absolute output data generating circuit 21 and
outputs switch data representing the detected state of operation of
each switch.
The push-button switches 8 and 9 correspond to switches mounted on
the conventional mouse 2, and when the switches are manipulated,
absolute output data is produced which is the same as that
generated by the manipulation of the switches on the mouse. The
operation unique to the mouse, such as drag, can be done by
manipulating the push-button switch 8 corresponding to the left
switch of the mouse.
The central control circuit 38 is connected to the mode decision
circuit 31, the stylus pressure detecting circuit 16, the output
side of the switch depression detecting circuit 22 and the
pressed-position data correcting and generating circuit 18. The
central control circuit 38 outputs to the absolute output data
generating circuit 21 the mode select signal fed from the mode
decision circuit 31 and the stylus pressure detection signal from
the stylus pressure detecting circuit 16 which represents the
pressing of the tablet sheet 6.
The absolute output data generating circuit 21, which is output
data generating means, generates absolute output data
(X.sub.n,Y.sub.n) of the format shown in Table 1 from the switch
data and the pressed-position data (x.sub.n,y.sub.n) or relative
position data (x.sub.n --x.sub.n-1,y.sub.n --y.sub.n-1). In Table 1
absolute values, each indicating the destination of the cursor
movement on the PC display 5 in a data format composed of five
bytes each consisting of 10 bits, are given as coordinate values X
and Y in the binary notation.
TABLE 1 ______________________________________ D7 D6 D5 D4 D3 D2 D1
D0 ______________________________________ First Bite P 1 F 0 0 0 S1
S0 Second Bite P 0 X5 X4 X3 X2 X1 X0 Third Bite P 0 X11 X10 X9 X8
X7 X6 Fourth Bite P 0 Y5 Y4 Y3 Y2 Y1 Y0 Fifth Bite P 0 X11 X10 X9
X8 X7 X6 ______________________________________
In Table 1, P is a parity bit and F is an effective area
designating bit. The effective area designating bit "0" indicates
that the tablet sheet 6 is being pressed within an effective
coordinate readout range, whereas "1" indicates that the tablet
sheet 6 is not being pressed within the effective coordinate
readout range. That is, when the bit F is "0," data is handled as
effective data. X0 to X11 (12 bits) are bits that represent the
abscissa value in binary notation, and Y0 to Y11 (12 bits) are bits
that represent the ordinate value in binary notation. The smaller
the numerical value, the less significant, and X0 and Y.sub.0 are
the least significant bits, respectively.
S0 and S1 are bits of the switch data representing the state of
operation of each of the push-button switches 8 and 9. For example,
when they are depressed, data of the corresponding bits S0 and S1
will change from "0" to "1."
Upon each application thereto of the mode select signal from the
central control circuit 38, the absolute output data generating
circuit 21 switches between the absolute value output mode and the
relative value output mode. In the absolute value output mode, the
absolute output data generating circuit 21 inputs thereinto
directly from the pressed-position data correcting and generating
circuit 18 the pressed-position data (x.sub.n,y.sub.n) composed of
12 bits for each of the X and Y coordinates and generates the
absolute output data (X.sub.n,Y.sub.n) using the input data as two
pieces of data composed of the bits X0 to X11 and Y0 to Y11,
respectively.
In the relative value output mode, the absolute output data
generating circuit 21 adds the relative position data (x.sub.n
--x.sub.n-1,y.sub.n --y.sub.n-1) output from the relative position
data calculating circuit 20 to the immediately preceding absolute
output data (X.sub.n-1,Y.sub.n-1) to generate new absolute output
data (X.sub.n,Y.sub.n). That is, the data (x.sub.n --x.sub.n-1) is
added to the coordinate value X.sub.n-1 expressed by the 12 bits X0
to X11 in the immediately preceding absolute output data
(X.sub.n-1,Y.sub.n-1), by which is generated the coordinate value
X.sub.n represented by the bits X0 to X11 in the new absolute
output data (X.sub.n,Y.sub.n). Likewise, the data (y.sub.n
--y.sub.n-1) is added to the coordinate value Y.sub.n-1 expressed
by the 12 bits Y0 to Y11 in the immediately preceding absolute
output data (X.sub.n-1,Y.sub.n-1), by which is generated the
coordinate value Y.sub.n represented by the bits Y0 to Y11 in the
new absolute output data (X.sub.n,Y.sub.n).
To generate the data in the relative value output mode, the
absolute output data generating circuit 21 is connected to an
absolute output data storage circuit 23, which stores therein the
absolute output data (X.sub.n,Y.sub.n) upon each generation
thereof. In the generation of new absolute output data
(X.sub.n,Y.sub.n) in the relative value output mode, the absolute
data generating circuit 21 calls up the immediately preceding
absolute output data (X.sub.n-1,Y.sub.n-1) stored in the storage
circuit 23.
Incidentally, in the relative value output mode, the absolute
output data (X.sub.n,Y.sub.n) is output only when the
pressed-position data (x.sub.n,y.sub.n) is continuously input
during the input of the stylus pressure detecting signal, that is,
only when shifting the position of pressing the tablet sheet 6
while pressing it. While no pressure is applied to the tablet sheet
6 and immediately after the detection of the stylus pressure, the
pressed-position data (x.sub.n,y.sub.n) is merely stored in the
storage circuit 10 and the absolute output data (X.sub.n,Y.sub.n)
is not output. Accordingly, the absolute output data output upon
removal of the stylus pressure to the tablet sheet 6 used as the
immediately preceding absolute output data (X.sub.n-1,Y.sub.n-1),
with the result that the cursor moves in a new press-shift
direction from the position where the stylus pressure was
removed.
The absolute output data (X.sub.n,Y.sub.n) generated by the
absolute output data generating circuit 21 is provided as send data
to the PC via an I/O interface 24 which is data output facilities.
The circuits surrounded by the broken lines in FIG. 4 are
integrated as a one-chip microcomputer together with the central
control circuit 38.
Next, a description will be given, with FIGS. 4 and 5, of the
operation of the touch pad 7 of such a configuration as described
above. FIG. 5 is an explanatory diagram showing the relationship
between the manipulation of the touch pad 7 and the cursor movement
on the PC display 5.
Assume that, as shown in FIG. 5, the cursor at "a'" on the display
5 is moved to an icon labeled with "Character Recognition" to cause
the PC 1 to perform character recognition. Based on absolute output
data (X0,Y0) corresponding to the position "a'" output in response
to the previous manipulation, the cursor is now being positioned at
the upper right corner of the display 5, but the cursor movement
can be controlled by pressing the tablet sheet 6 with a finger
while shifting it from the position "b" to "c" at substantially the
center of the sheet 6. When the tablet sheet 6 is pressed at the
position "b," the pressure applied thereto is detected and, at the
same time, the contact resistance value r.sub.P by pressing is
detected. Since the tablet sheet 6 is being pressed with the
finger, the contact resistance value r.sub.P is greater than the
afore-mentioned boundary value r.sub.TP. Hence, the mode decision
circuit 31 decides that the mode of operation is the relative value
output mode, and the absolute output data generating circuit 21
goes into the relative value output mode accordingly.
On the other hand, pressed-position data on "b" is detected by the
pressed-position detecting circuit 17, but since the stylus
pressure has just been detected, the pressed-position data
(x.sub.0,y.sub.0) is merely stored in the pressed-position data
storage circuit 19 and the absolute output data (X.sub.n,Y.sub.n)
is not output. By the press-shift of the finger toward the position
"c," new pressed-position data (x.sub.1,y.sub.1) is detected and
the relative position data calculating circuit 20 calculates
relative position data (x.sub.1 --x.sub.0,y.sub.1 --y.sub.0) from
the immediately preceding pressed-position data (x.sub.0,y.sub.0)
and the pressed-position data (x.sub.1,y.sub.1) newly fed from the
pressed-position data correcting and generating circuit 18.
Since the absolute output data generating circuit 21 is in the
relative value output mode, it adds the relative position data
(x.sub.1 --x.sub.0,y.sub.1 --y.sub.0) to the immediately preceding
absolute output data X.sub.n-1,Y.sub.n-1) to obtain new absolute
output data (X.sub.1,Y.sub.1). The immediately preceding absolute
output data was not generated when the tablet sheet 6 was pressed
at the position "b," and hence it is the absolute output data
(X.sub.0,Y.sub.0) corresponding to the position "a'." That is, X1
becomes X.sub.0 +(x.sub.1 --x.sub.0) and Y1 becomes Y.sub.0
+(y.sub.1 --y.sub.0), so that the cursor moves from the position
"a'." Thus, by shifting the finger from the position "b" toward "c"
at the center of the tablet sheet 6 while pressing the finger
thereto, it is possible to control the cursor to move from the
position "a'" toward the icon labeled with "Character Recognition."
In this movement control, the cursor can be continuously moved even
if the pressing of the tablet sheet 6 is temporarily stopped.
Upon depression of the push-button switch 8 after moving the cursor
to the icon labeled with "Character Recognition," the PC 1 executes
a character recognition processing program and goes into a
character input waiting state. The character input is provided by
writing a desired character on the tablet sheet 6 with a
stylus.
Assuming that a character "" is input by the stylus and the tablet
sheet 6, the stylus is press-shifted on the tablet sheet 6 from the
position "e" to "f." When the tablet sheet 6 is pressed at the
position "e," it is detected together with the contact resistance
value r.sub.P. Since the tablet sheet 6 is pressed by the stylus,
the area of contact between the resistance sheets 60 and 6a is
smaller than in the case of being pressed by a finger and the
contact pressure per unit area increases accordingly and the
contact resistance r.sub.P becomes smaller than the boundary value
r.sub.TP.
Hence, the absolute value output mode is decided upon by the mode
decision circuit 31 and the absolute output data generating circuit
21 is put in the absolute value output mode.
On the other hand, the pressed-position data (x.sub.0,y.sub.0) at
the position "e" is detected by the pressed-position detecting
circuit 17 and the absolute value output data generating circuit 21
uses the pressed-position data (x.sub.0,y.sub.0) intact to generate
the absolute output data (X.sub.0,Y.sub.0). As a result, the cursor
at the icon "Character Recognition" is displayed at a position "e'"
on the display 5 which corresponds to the pressed-position data
(x.sub.0,y.sub.0). Likewise, when the stylus is moved from the
position "e" to "f," absolute output data (X.sub.n,Y.sub.n)
containing the pressed-position data (X.sub.n,Y.sub.n) at the
pressed position is output and the cursor moves from the position
"e'" to "f'" in correspondence with the pressed position. Removing
pressure from the tablet sheet 6 at the position "f" and pressing
it again at a position "g," absolute output data (X.sub.n,Y.sub.n)
containing pressed-position data (x.sub.n,y.sub.n) at the position
"g" is output and the cursor moves to a position "g'" corresponding
to the position "g." That is, even if the tablet sheet 6 is pressed
at the position "g," after the suspension of the cursor movement by
the removal of pressure at the position "f," the cursor will not
move again from the position "f'," so that a character with
separate strokes can be input by a sequence of steps which do not
involve any particular input operations.
Incidentally, the PC 1 judges that the press-shift of the stylus
from the position "e" to "f" is a stroke of the character being
input because the effective area designate bit F is "0" and that
the shift from the position "f" to "g" is a mere cursor movement
because the bit F is "0." In response to the press-shift from the
position "g" to "h" the cursor similarly moves from the position
"g'" to "h'."
To indicate the mode of operation of the absolute output data
generating circuit 21, the light emitting elements 11 and 12 stay
lit up during the relative value output mode and during the
absolute value output mode, respectively.
The pressure sensitive resistance tablet coordinate input device
according to the first embodiment described above provides the
absolute output data (X.sub.n,Y.sub.n) in the same format as that
used for the tablet, but since the device driver, which is
connected to the mouse, is to move the cursor on the basis of the
relative output data (X'.sub.n,Y'.sub.n), it cannot be connected to
the PC 1 in a manner to be compatible with the mouse.
FIG. 6 illustrates in block form a second embodiment of the
pressure sensitive resistance tablet coordinate input device
according to the present invention, which is designed to provide
the relative output data (X'.sub.n,Y'.sub.n) of the same format as
that for the mouse. In FIG. 6 the parts corresponding to those in
the first embodiment are identified by the same reference numerals
and their description will not be repeated.
As is evident from comparison with the touch pad 7 of the first
embodiment, the touch pad 30 of this embodiment differs therefrom
in that the absolute output data storage circuit 23 is omitted,
that the output data generating facilities is connected to the
pressed-position data storage circuit 19 in place of the
pressed-position data correcting and generating circuit 18 and that
the output data generating facilities is a relative output data
generating circuit 39.
Upon each application thereto of a mode select signal from the
central control circuit 38, the relative output data generating
circuit 39 switches between the absolute value output mode and the
relative value output mode.
When the relative output data generating circuit 39 is in the
absolute value output mode, it generates relative output data
(X'.sub.n,Y'.sub.n) from relative position data (x.sub.n
--x.sub.n-1,y.sub.n --y.sub.n-1) calculated from the difference
between pieces of pressed-position data (x.sub.n,y.sub.n)
continuously input thereinto at all times. That is, upon newly
detecting the stylus pressure to the tablet sheet 6 after it was
temporarily removed, relative position data (x.sub.1
--x.sub.0,y.sub.1 --y.sub.0) calculated from the difference between
pressed-position data (x.sub.0,y.sub.0) at the pressure-removed
position and pressed-position data (x.sub.1,y.sub.1) at the
pressure-detected position are used to generate relative output
data (X'.sub.1,Y'.sub.1), which is fed to the PC 1. As a result,
the amount of relative movement with no stylus pressure is provided
to the PC 1, so that the cursor is controlled to apparently move to
the position corresponding to the pressed position of the tablet
sheet 6. For example, where the stylus pressure is removed from the
tablet sheet 6 at the position "f" and is applied thereto again at
the position "g," the cursor moves from the position "f'" to "g'"
as in the first embodiment.
On the other hand, while in the relative value output mode, the
relative output data generating circuit 39 does not generate the
relative output data (X'.sub.1,Y'.sub.1) when the stylus is
supplied with a new stylus pressure detection signal from the
central control circuit 38. In other words, the pressed-position
data (x.sub.n-1,y.sub.n-1) stored in the pressed-position data
storage circuit, namely, the pressed-position data
(x.sub.0,y.sub.0) at the position where the stylus pressure applied
to the tablet sheet 6 was removed therefrom, is rewritten to
pressed-position data (x.sub.1,y.sub.1) at the position where the
pressure was newly detected, but since the relative output data
(X'.sub.1,Y'.sub.1) based on the relative position data (x.sub.1
--x.sub.0,y.sub.1 --y.sub.0) is not created, the amount of relative
movement with no stylus pressure is not fed to the PC 1. Unless the
stylus pressure is detected, the same processing as in the absolute
value output mode is done, and when supplied with new
pressed-position data (x.sub.2,y.sub.2) after further press-shift,
the relative output data generating circuit 39 generates relative
output data (X'.sub.2,Y'.sub.2) based on relative position data
(x.sub.2 --x.sub.1,y.sub.2 --y.sub.1) and provides it to the PC 1.
Thus, even if the stylus pressure to the tablet sheet 6 is once
removed, the cursor moves from the pressure-removed position, so
that the cursor movement can be controlled continuously.
As described above, according to the second embodiment of the
invention, either the relative value output just like a mouse
output or the absolute value output just like a tablet output can
be selected in accordance with the content of each input operation,
and hence the output data can be fed to the PC 1 in a format
suitable for subsequent processing. Additionally, this mode
selection can be made by pressing the tablet sheet 6 with either a
stylus or finger. In other words, no particular operation or input
facilities is needed.
While in the above the mode of operation of the output data
generating facilities is selected by changing the contact
resistance value r.sub.P, depending on whether a finger or stylus
is used to press the tablet sheet 6, the invention is not limited
specifically thereto. It is possible to use any facilities which
provide different resistance values, such as two kinds of styluses
whose tip end portions of different curvatures, or the tablet sheet
6 may be pressed by a finger and a finger tip.
The pressure facilities may also be a single stylus or finger, in
which the pressure applied to the tablet 6 needs only to be changed
so that the contact resistance value r.sub.P is changed accordingly
to select the mode of operation of the output data generating
facilities.
In the above, upon each detection of the X- and Y-coordinates, the
contact resistance value r.sub.P is detected and the mode of
operation of the output data generating facilities is decided, but
the invention is not limited specifically thereto. The mode of
operation may also be changed by detecting the contact resistance
value r.sub.P when the application of the stylus pressure to the
tablet sheet 6 is newly detected or when the removal of the
pressure is detected.
EFFECT OF THE INVENTION
As described above, according to the first aspect of the present
invention, in the absolute value output mode the pressed-position
data (x.sub.n,y.sub.n) can be used intact as the absolute output
data (X.sub.n,Y.sub.n), so that the cursor can be moved to a
desired position by pressing the tablet sheet only once at the
position corresponding to the cursor destination. In the relative
value output mode, since the relative position data (x.sub.n
--x.sub.n-1,y.sub.n --y.sub.n-1) can be used to obtain the absolute
output data (X.sub.n,Y.sub.n), the press-shift operation of the
stylus can be made on an arbitrary sheet. Whether to put the output
data generating facilities in the absolute or relative value output
mode can easily be selected only by changing the pressure to the
tablet sheet 6 to change the contact resistance value r.sub.P at
the pressed position. Accordingly, neither mode select switch nor
mode switching operation is needed for the mode selection.
According to the second aspect of the invention, in the absolute
value output mode, the relative output data (X'.sub.n,Y'.sub.n) is
generated from the relative position data (x.sub.n
--x.sub.n-1,y.sub.n --y.sub.n-1) indicating the relative position
while no pressure is applied to the tablet sheet 6, the cursor can
be moved to a desired position simply by pressing the tablet sheet
6 at the position apparently corresponding to the cursor
destination. In the relative value output mode, since the relative
output data (X'.sub.n,Y'.sub.n) is not created using the relative
position data indicating the relative position while the pressure
is not applied to the tablet sheet 6, control of the cursor
movement can be continued from the current position of the cursor,
even if the pressure to the tablet sheet 6 is once removed. Whether
to put the output data generating facilities in the absolute or
relative value output mode can easily be selected only by changing
the pressure to the tablet sheet 6 to change the contact resistance
value r.sub.P at the pressed position. Accordingly, neither mode
select switch nor mode switching operation is needed for the mode
selection.
According to the third and fourth aspect of the invention, the
absolute or relative output mode can easily be selected by changing
the contact resistance value r.sub.P.
According to the fifth aspect of the invention, once the absolute
value output mode or relative value output mode is selected
according to the contact resistance value r.sub.P at the position
where the tablet sheet 6 is pressed again after removing the
pressure therefrom, it is possible to select whether to continue
the cursor movement or to directly move the cursor to a
predetermined position on the display, even if the pressure to the
tablet sheet 6 is removed.
It will be apparent that many modifications and variations may be
effected without departing from the scope of the novel concepts of
the present invention.
* * * * *